If this has fascinated you as it has me I would recommend reading Written In Blood by Diane Fanning. I have only just started it but there is already so much detail about the autopsy report that points to the fact that she was attacked and beaten. For examples there were marks around her thyroid that are typical of strangulation and there was a bloody footprint on the back of her leg. None of this was mentioned in the trial part of the documentary, perhaps it was edited out. There is also information about the son Todd’s behaviour on the night of Katherine’s death.
I have borrowed the book from an online library archive.com. You usually have to wait for a book to become available but they notify you when it is and you have two weeks to read it on line.